Large-scale prawn culture has been developed since 1970s-1980s. The coastal area of China, from south to north, has large output of prawn, and this promotes the growth of economy. Nowadays, virus infection poses a grave threat to prawn culture and leads to great economic losses of prawn culture farms. Taura Syndrome Virus (TSV) and White Spot Syndrome Virus (WSSV) infections are two major infectious diseases which seriously endanger the healthy development of prawn culture industry. According to a prawn disease report from the World Bank, viral diseases were responsible for 74% reduction of output in prawn culture and caused more than 3 billion dollars of economic losses all over the world in 1994. In 1995, these diseases were listed by OIE (International Office of Epizootics), FAO (Food and Agriculture Organization of the United Nations) and NACA (Network of Aquaculture Centre in Asia-Pacific) as one of the aquatic animal viral plagues that need to be reported.
WSSV infection was first found in Taiwan in 1992 and it broke out in prawn culture farms from south to north along the coast of Mainland China between May and August of 1993, and then it broke out in other Asian countries such as Japan. At present, WSSV infection has been reported to prevail in countries and regions including North Korea, Thailand, South Korea, Indonesia, Vietnam, Malaysia, India, Sri Lanka, Bangladesh, coastal areas of Mainland China and Taiwan, etc. In 1995, WSSV was found in prawn culture farms in Texas, U.S.A., and then prevailed in other regions of the western hemisphere. From then on, WSSV infection spreads worldwide and causes tens of billions of economic losses of prawn culture industry every year, and it becomes the major disease which threatens the prawn culture industry.
With the increase of market demands and improvement of rearing techniques, aquaculture industry has developed rapidly in China. However, as the requirements for quality become higher and higher in both domestic and overseas markets, safety barriers are gradually built for aquatic products in China because of drug residues exceeding standard from time to time, as well as the higher probability of carrying viruses, bacteria, parasites and biotoxins in the aquatic products. Prawns are invertebrates and resist to pathogenic invasions mainly through non-specific immunity including cellular and humoral immunities. These two immunities relate closely to each other, wherein humoral immunity factors are synthesized and released by blood cells, cellular immunoreactions in turn are mediated and affected by humoral immunity factors. Immunopotentiators are now mainly used to promote or induce defense reactions in host (prawns) and enhance the resistance against diseases. Therefore, although vaccination can achieve good results in vertebrates, it is especially important to develop a new method for treatment and prevention of prawn diseases in prawns.
Contents of the Invention
The present invention aims to provide a nucleic acid drug that can kill WSSV and/or TSV directly, and has good antiviral effects without toxic or side effects, drug tolerance, or drug residues.
The anti-WSSV and/or TSV nucleic acid drug provided by the invention has active components of 5 nucleic acids, the sequences of which are respectively SEQ ID NOs: 1, 2, 3, 4, and 5.
The anti-WSSV and/or TSV nucleic acid drug of the invention has any mass ratio of the 5 nucleic acids.
The anti-WSSV and/or TSV nucleic acid drug of the invention has a mass ratio of the 5 nucleic acids of 1:1:1:1:1.
The anti-WSSV and/or TSV nucleic acid drug of the invention also comprises pharmaceutically acceptable vectors or excipients.
The anti-WSSV and/or TSV nucleic acid drug of the invention can specifically kill WSSV and/or TSV directly, and has good antiviral effects without toxic or side-effect, drug tolerance, or drug residues. The nucleic acid drug can control WSSV and/or TSV infections in prawns and prevent massive deaths, therefore, reducing risks in prawn culture. Meanwhile, the present drug avoids the problem of drug residues exceeding standard caused by chemical drugs against viruses and bacteria, and improves quality of prawn products.